- on Metacritic numbers:

According to Metacritic, the PS4 has the highest average score for its titles, notwithstanding those on the PC of course.

The average score for all the PS4 games tallied is at 70.5, which is just slightly higher than that of the Xbox One.

The PS4 console has over 70 games more than the Xbox One and almost 100 more than other platforms...

- on PS4 catalogue having an influence on sales performance:

We would assume that the superiority of the PS4 catalog is one major contributor to its sales performance.

http://www.dailysunknoxville.com/playstation-4-vs-xbox-one-which-has-better-games/20155556

Yes, this is part two of this:

http://gamrconnect.vgchartz.com/thread.php?id=211619&page=1

Metacritic is bs. How can the same game have to different scores on different systems? It makes no sense.

they wrote something on that:

One could contest that the Xbox One’s version of Metal Gear V: The Phantom Pain held the top rating, but on the other side it can be put forth that it’s the quality across the console’s roster that matters more. We’ll leave that for the apologists to argue.

Actually, it does. While it may be less apparent now that the XB1 and PS4 are similar, there are still minor differences across the two consoles. For example, last generation the 360 version of Bayonetta ran much better than the PS3 version. In the 5th generation and earlier the differences were even more notable.

Because one console runs it better than another?

Says mgs5 at 720p vs 1080p?

Well there hasnt really been much fo that this generation but games  like Minecraft and shovel knig all did better on ps4 and hsovel knight did lower on pc than ps4, wtf?

Well games like Shovel Knight got a better ranking on ps4 when the xbox one and wii u and more content than the playstation version. Wii U got amiibo and X1 got extra content since it launched late.

Excuse me? Never got this metacritic hate when all it does is just compile scores from other reviewers. 

But to answer your post, I would think it makes perfect sense how the same game can have different scores on different platforms. If the game runs better on one platform, shouldn't it get a higher score on that platform?

There are different reviews, from console specific sites that contribute to this. Like say, Xboxfurries.org giving one game an 8, while PSdiaperfetishist.com gives it a 9.5.

Are you being serious?